Embodiments of the present invention generally relate to medical imaging devices, and more particularly, to methods and systems of acquiring images with medical imaging devices.
Medical imaging techniques, including X-ray, Computerized Axial Tomography (CAT), and ultrasound are well established. With these techniques, an examining physician is provided with high resolution images that assist the examining physician to perform subsequent detailed study and diagnosis.
Additionally, surgical navigation systems are used to track the location of a medical instrument within an operating environment. Such systems provide pre-operative images for improving intra-operative visualization of an anatomical structure of a patient. Intra-operative image data acquisition enables determination of a precise spatial correlation between an image data and the anatomical structure of the patient.
For example, identifiable landmarks may be formed on, or attached to, a fluoroscopic C-arm, and to the patient, or a frame, or a table on which the patient is positioned. These identifiable landmarks are typically visible in the images. Further, these identifiable landmarks are typically clearly identifiable and registered to the patient. Fiducial landmarks may be attached to the patient a day prior to surgery, to enable CT measurements for planning and intra-operative navigation purposes. During the surgery, the landmark points are identified in the images, and at least three pairs of the corresponding points are localized on the patient for subsequent use with the help of a navigation system. The co-ordinate transformation between the image data and the patient is determined from the corresponding pairs of points, which are usually at least three.
In known medical imaging devices, it is difficult to accurately position the medical imaging device at the center of the anatomy of interest without the use of continuous X-rays or multiple X-ray exposures. Further, the image may be rotated in an orientation in a manner that is different from the orientation at which the examining physician is attempting to perform the surgery. Some known medical imaging devices use integrated or add-on laser aiming devices to minimize the amount of X-ray exposure that is required to achieve the desired anatomical position. These known medical imaging devices only indicate target surfaces, and do not predict the precise alignment of the patient and the C-arm. Further, these known medical imaging devices employ X-ray radiation, which is known to have an accumulative negative effect on human health.